THE IRRIGATION AGE. 



691 



THE PRIMER OF HYDRAULICS* 



By FREDERICK A. SMITH, C. E. 



Introduction. 



Everything round about us which makes its presence 

 known to us by acting upon our senses is called Nature. 

 Thus nature is the sum total of everything capable of making 

 an impression upon the human senses. It may be divided 

 into two large subdivisions, namely, Things and Phenomena, 

 and the knowledge of them is called Natural History and 

 Natural Science respectively; thus the knowledge of animals, 

 vegetation and minerals is called Natural History, subdivided 

 into Zoology, Botany and Mineralogy, The knowledge of 

 phenomena, such as the flowing of water in a river, or the 

 freezing of water, or the rusting of iron and the growing of 

 vegetation, is called Natural Science. The many thousands 

 of phenomeria in nature can be divided into two great classes. 

 The one class embraces phenomena wlrch do not change the 

 constitution of the things upon which they are observed; for 

 instance, the sounding of a bell, the breaking of a glass, the 

 falling of an apple, the melting of wax, the boiling of water, 

 are all phenomena which do not change the character of the 

 substances involved; thus the bell is still a bell after sound- 

 ing; the broken glass is still glass, the apple is still an apple 

 after its fall, the wax is still wax after it is melted and the 

 stream is still water after condensation. Such phenomena 

 are called Physical Phenomena and the science teaching their 

 knowledge is called Physics. 



The other class of phenomena always produces a change 

 in the affected bodies ; for instance, if a copper coin is im- 

 mersed into nitric acid there will be observed an intense 

 action, the fluid turning green with a rising of brown vapor, 

 and if enough nitric acid is used the entire copper coin dis- 

 appears ; if the green liquid is boiled down crystals of a green 

 substance appear, which are neither copper nor nitric actd, 

 but is a new substance called copper nitrate ; thus the phe- 

 nomenon has changed the constitution of the copper as well 

 as that of the nitric acid; such phenomena are called chemical 

 phenomena and the science treating of them is called Chem- 

 istry. Some other chemical phenomena are, for instance, 

 the rusting of iron, the burning of wood, and the various 

 processes of life in animals and plants, the manufacture of 

 glass, reduction of ores, etc. 



From the foregoing it is apparent that the phenomena of 

 Hydraulics, upon which this work will treat principally, be- 

 long into the field of Physics, as the act : on of the forces 

 which produce pressure and flow in water and other fluids 

 does not produce a chemical change in its constitution. As this 

 book is intended to treat the subject of Hydraulics in a prac- 

 tical way, adapted to the needs and capacities of the practical 

 men who follow the various application of Hydraulics, the 

 author will devote some time to the most important element- 

 ary principles underlying this subject, as an understanding of 

 them is necessary for the comprehension of Hydraulics and 

 its application to practical problems. 



Art. 1. General Properties of Matter. 



Everything which possesses weight is called matter. Even 

 the lightest substance known, Hydrogen Gas, has weight, 

 but one cubic inch of Hydrogen Gas weighs only the 11,000th 

 part of a cubic inch of water, and a cubic inch of air is 



nearly 14^2 times as heavy as a like quantity of Hydrogen 

 Gas. 



Following are the general properties of matter : 



1. Extension. This means that all matter requires space 

 for its existence. This is self-evident. 



2. Impenetrability. This means that two bodies cannot 

 occupy the same space at the same time. 



3. Divisibility. This means that all matter can be divided 

 into smaller parts; the truth of this is also self-evident. Thus 

 if we crush a piece of chalk until it is a fine powder and look 

 at it through a strong microscope, we observe that the appar- 

 ently fine powder is composed of lumps of different forms, 

 and though we are practically unable to break them into 

 smaller parts, we can readily imagine that such division can 

 be carried on much further. By the same process of reason- 

 ing a limit of divisibility must, however, be reached some 

 time, or, with other words, there must be a smallest particle 

 of every kind of matter. Such smallest particle is called a 

 Molecule, 



Some kinds of substances are composed all through of 

 just one kind of matter; for instance, the diamond, which is 

 pure carbon, while other substances are composed of two or 

 more kinds of matter, as, for instance, water. Bodies com- 

 posed of but one kind of matter are called Elements, while 

 such bodies as are composed or two or more elements are 

 called Compounds. If the divisibility in an element is carried 

 on in imagination until the smallest particle is reached, then 

 we are face to face with the Atom; hence an atom can be 

 denned as the smallest particle of matter which can be divided 

 no further. On the other hand, the smallest particle of a 

 compound, the molecule, can be divided into the elementary 

 atoms composing it. For instance: Water is composed of 

 two elements, Oxygen and Hydrogen, and it may be decom- 

 posed by an electric current into these two elements; when 

 this is done the Hydrogen gas appears on one electrode and 

 the Oxygen on the other; also the volume of the Hydrogen 



gas which 

 tube B, 

 equal to 

 volume of 

 rising in 

 this shows 

 every atom 

 there are 

 of Hydro- 

 molecule of 

 elementary 

 resented by 

 Vhe letter 



Fig. I. 



appears in 

 Fig. 1, is 

 twice the 

 the Oxygen 

 tube A; 

 that for 

 of Oxygen 

 two atoms 

 gen in a 

 water. The 

 atom is rep- 

 a symbol, 



*Copyright by D. H. Anderson, December, 1910. 



O" in chemical lore represents an atom 

 of Oxygen the letter H represents an atom of Hydrogen, so 

 that the chemical symbol for water is H 2 O, which means that 

 the molecule of water consists of two atoms of Hydrogen 

 and one atom of Oxygen. This symbol also tells the weight 

 relation between the two elements, which is done by a table 

 of atomic weights in which the relative weight of the various 

 elements are compared with that of Hydrogen, whose weight, 

 being the lightest substance known, is taken as unity; thus 

 the atomic weight of Oxygen is 16, which means that the 

 Oxygen atom is 16 times heavier than Hydrogen. This then 

 gives the information that if, for instance, 9 pounds of water 

 are decomposed into Oxygen and Hydrogen, we obtain 8 

 pounds of Oxygen and one pound of Hydrogen. 



Water has purposely been chosen as an example, as this 

 work will deal principally with water and its properties, and 

 therefore the reader should increase his knowledge constantly 

 in this direction. 



